Alert archive / California / Flash Flood Warnings in 2020

Flash Flood Warning 9, NWS Reno, NV

July 20, 2020Plumas County, California

NWS Reno, NV issued this flash flood warning at Jul 20, 2020, 7:56 PM PDT for Plumas County, California. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 20, 2020, 7:56 PM PDT (02:56 UTC)
Expired: Jul 20, 2020, 10:11 PM PDT
In force: 2 hr
Issued by: NWS Reno, NV
Area: Storm-based polygon
Flood severity: None

County Plumas County, CA

The radar

The Reno radar (KRGX), 105 km from the middle of the area, began a volume at 02:58 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Reno, NV (KREV), launched 00:00Z, 2.9 hours before the alert went out and 214 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 111 J/kg
Mixed-layer CIN: -10 J/kg
Mixed-layer LCL: 3995 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: -13 m²/s²
0-3 km storm-relative helicity: -27 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

779 
WGUS55 KREV 210256
FFWREV
CAC063-210600-
/O.NEW.KREV.FF.W.0009.200721T0256Z-200721T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Reno NV
756 PM PDT Mon Jul 20 2020

The National Weather Service in Reno has issued a

* Flash Flood Warning for...
  Plumas County in northern California...

* Until 1100 PM PDT.

* At 754 PM PDT, Doppler radar indicated thunderstorms producing
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly within and just downstream of the Walker 
  Fire burn scar.

  HAZARD...Flash flooding and debris flow caused by thunderstorms.

  SOURCE...Radar indicated.

  IMPACT...Flooding of small creeks and streams, urban areas, 
           highways, streets and underpasses as well as other 
           drainage and low lying areas.

* Some locations that will experience flooding include...
  Eastern Genesee, Antelope Lake and Long Point Campground. 

Excessive rainfall over the Walker Fire burn scar will result in 
debris flow. The debris flow can consist of rock, mud, vegetation 
and other loose materials.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Move away from recently burned areas. Life-threatening flooding of 
creeks, roads and normally dry water crossings is likely. The heavy 
rains will likely trigger rockslides, mudslides and debris flows in 
steep terrain, especially in and around these areas.

&&

LAT...LON 4017 12052 4009 12054 4001 12059 4001 12070
      4008 12071 4019 12065

FLASH FLOOD...RADAR INDICATED

$$

MB

1 follow-up statement

102 
WGUS75 KREV 210511
FFSREV

Flash Flood Statement
National Weather Service Reno NV
1011 PM PDT Mon Jul 20 2020

CAC063-210519-
/O.CAN.KREV.FF.W.0009.000000T0000Z-200721T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Plumas CA-
1011 PM PDT Mon Jul 20 2020

...THE FLASH FLOOD WARNING FOR PLUMAS COUNTY IS CANCELLED...

The heavy rain has ended. While new flooding is no longer expected 
to pose a threat, there could be washed out roadways that would be 
difficult to see during the overnight hours. Rivers and streams will 
continue to run fast for the next several hours as well. Please 
continue to heed any remaining road closures.

LAT...LON 4017 12052 4009 12054 4001 12059 4001 12070
      4008 12071 4019 12065

$$

MB

The office that day

Everything else NWS Reno, NV issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 20, 5:15 PM PDT	Severe Thunderstorm Warning	REV	Placer	30 min
Jul 20, 7:20 PM PDT	Severe Thunderstorm Warning	REV	Plumas	25 min
Jul 20, 7:41 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	34 min
Jul 21, 2:06 PM PDT	Special Weather Statement	REV	Alpine, Lassen, Mono, Plumas	99 min
Jul 21, 3:33 PM PDT	Severe Thunderstorm Warning	REV	Plumas	42 min
Jul 21, 3:50 PM PDT	Special Weather Statement	REV	Alpine, Lassen, Mono	115 min
Jul 21, 3:52 PM PDT	Severe Thunderstorm Warning	REV	Alpine	38 min
Jul 21, 4:07 PM PDT	Severe Thunderstorm Warning	REV	Lassen, Plumas	53 min
Jul 21, 4:22 PM PDT	Flash Flood Warning	REV	Plumas	3 hr
Jul 21, 4:39 PM PDT	Severe Thunderstorm Warning	REV	Lassen	51 min

Nearby

Flash Flood Warnings in California, 2020 Every flash flood warning in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.